Product and process

ABSTRACT

A slub yarn product is prepared by a process in which a core strand is advanced through a series of false-twisting devices so as to form rotating standing waves ahead of each false-twister and simultaneously feeding yarns to the advancing core at the rotating waves to form a wrapped layer extending all along the core. Slubs are provided by feeding a sliver of discontinuous fibers to the core at a rate which causes the sliver to be intermittently caught in the advancing core and broken into separated portions which become part of the wrapped core. Slubs can also be produced by intermittently advancing the core strand through the wrapping operation to provide a wrapped layer of varying thickness. Slub size and spacing may be random or substantially uniform. The slubs are generally 15 to 35% greater in cross-sectional area than nonslubbed portions, 2 to 5.5 inches long, and spaced 8 to 30 inches between slubs.

Dunwoody, Jr.

[ 1 PRODUCT AND PROCESS Primary ExaminerDonald E. Watkins [75] Inventor:Samuel A. Dunwoody, Jr.,

Martinsville, Va. [57] v ABSTRACT 4 [73] Assignee: E.I. du Pont deNemours and A slub yarn product is prepared by a process in whichCompany, Wilmington, Del. a core strand is advanced through a series offalsetwisting devices so as to form rotating standing waves [22] B Sept1972 ahead of each false-twister and simultaneously feeding [21] Appl.No.: 286,134 4 yarns to the advancing core at the rotating waves to forma wrapped layer extending all along the core. Slubs are provided byfeeding a sliver of discontinuous [52] US. Cl. 57/144, 57/160 fibers tothe core at a rate which causes the Sliver to g be intermittently caughtin the advancing core and I 0 care l g J 156 6 broken into separatedportions which become part of 16 the wrapped core. Slubs can also beproduced by interrnittently advancing the core strand throughthe [56-]References C'ted wrapping operation to provide a wrapped layer of U T DSTATES PATENTS varying thickness. Slub size and spacing may be ranl,997,77l 4/1935 McGowan... 57/144 dom or substantially uniform. The slubsare generally 3,332,227 7/1967 Marshall 57/140 J X 15 to 35% greater incross-sectional'area than non- 3'174371 3/1965 Edwards et a1; 57/140 1slubbed portions, 2 to 5.5 inches long, and spaced 8 to 3,427,647 2/1969Field r r r v 57/144 30 inches between Slubs 3,675,409 7/1972 RosenstcinH 57/144 10 Claims, 5 Drawing Figures ps0 N r PRODUCT AND PROCESS FIELDOF INVENTION This invention relates to wrapped slub yarns ofa typeespecially suitable for weaving upholstery fabrics, and to a process formaking slub yarns.

Field-US. Pat. No. 3,427,647 dated Feb. l 1,1969, discloses a processfor preparing a wrapped yarn product by continuously advancing a corestrand through one or more false-twisting devices to form a rotatingstanding wave pattern of multiple balloons in the core strand and freelyfeeding wrapping yarns to the rotating standing waves to wrap around thecore. The nature of the wrapped layer formed about the core can becontrolled by the core strand tension, denier, forwarding speed androtational velocity, as well as the number and denier of the wrappingyarns.

SUMMARY OF THE INVENTION I In accordance with the present invention slubyarns are produced by the improvement in the above process of feeding asliver of discontinuous fibers to the core strand, at a lower rate thanthe rate of advancing the core, so that the sliver is intermittentlycaught in the core and caused to break into portions spaced along thecore, and is then wrapped as part of the core to form slubs in thewrapped yarn product. Preferably, a jet device is used to feed thesliver to the advancing core in ajet of air. When a plurality of strandsare continuously combined to form the advancing core, the

slub-forming sliver is preferably fed to the core between combiningstrands. The average slub size and spacing is controlled by the sliversize and rate of feed to the core. The wrapping conditions arepreferably controlled to produce a wrapped layer which extendscompletely along the core with wrapping yarns winding about the corealternately is S and Z twist directions and backwinding about previouswindings in tight portions at random intervals along the core.

The slub yarn product of this invention has a fibrous core and a wrappedlayer of continuous yarns which extends completely along the core. Theroduct is char acterized by slubs which have cross-sectional areas from15 percent to percent greater than the average cross-sectional area ofthe nonslubbed portions. The slubs'may be 2 to 5.5 inches long with adistance of 8 to 30 inches between slubs. The product is alsocharacterized by a wrapped layer of wrapping yarns winding about thecore alternately in S and Z twist directions and backwinding aboutprevious windings in tight portions at random intervals along the core.The wrapping yarns may be of continuous filaments or spun yarn, or both.The core may be composed of discontinuous tibers in the form of sliver,roving or spun yarn, and may include continuous filaments. Preferably,the core is formed of a plurality of strands of discontinuous fibers andthe slubs result from a greater number of core fi bers in slub portionsthan in nonslubbed portions of the product. In a particularly desirableproduct, the slubs have random lengths between 2 and 5.5 inches and arerandomly spaced at distances of 8 to 30 inches between slubsv Forupholstery fabrics, the slubbed yarn product preferably has a corebetween 5,000 and 9,000 denier in size, of discontinuous fibers, wrappedwith continuous-filament yarns to a denier between 6,000 and 10,000 forthe slub yarn product.

The slub yarn product may be characterized by a wrapped layer which hasa preponderance of wrappings at slub portions of the product. Slubs canbe produced by intermittently advancing a core strand through thewrapping operation to provide a wrapped layer of varying thickness.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representationof a process of this invention.

FIG. 2 is a representation of a section offa wrapped slub yarn productof this invention.

FIG. 3 illustrates a modification of the core-forming operation of FIG.1.

FIG. 4 illustrates a modification of the wrapping operation of FIG. 1.

FIG. 5 is a representation of a section of slub yarn product having apreponderance of wrappings at the slub portion. t i

DESCRIPTION OF PREFERRED EMBODIMENTS In the process of FIG. 1, allmovement of the core 10 through the apparatus is provided by theconstant peripheral velocity of driven package 14 resting againstsmoothing roller 12 Core strands 16, unwound from supply package 18, areled around tension bars 20 into the rotating standing-wave pattern 22upstream of first torquejet false twister 24. Partially wrapped yarn 30passes through the longitudinal passage of twister 24 in which it isfalse-twisted by a vortex of air generated by injecting air tangentiallyinto the passage through pipe 26. A plurality of spacedcontinuous-filament wrapping yarns 32 from creel 34 issimultaneously fedto the standing-wave pattern 22. Partially wrapped yarn continuesthrough the second rotating standing-wave pattern 36 established bytorque-jet false twister 38 just as was'done by twister 24 except thatair inlet 40 is reversed to produce an oppositely rotating vortex. Asecond set of wrapping yarns 42 is simultaneously fed to standing-wavepattern 36'from creel 44. A snubbing guide 46 prevents the twist oftwister 38 from influencing the operation of twister 24. Fully wrappedyarn 5O is led around guide 48 to wind-up on package 14 which,

in this embodiment,

velocity. i

The formation of slubs in the process of FIG. I involves discontinuousaddition of sliver to the core. Package 56 of sliver 58 is mounted sothat the free end of sliver-may be forwarded by driven nip rollers 52into a forwarding jet of air in jet-device 54. The jetdevice 54discharges sliver 58 so close to running core 10 that the free'end ofsliver 58 must contact and be caught in core 10. The sliver 58 to beemployed is a carded, untwisted rope of discontinuous fibrous materialwhich has a low breaking strength. Nip rollers 52 are operated so thatthe linear velocity of advance of sliver 58 is less than that of core10. Thus, when the free end of sliverchanges in the wrapped product. Thelength of each slub is most directly determined by the distance be-'tween the nip rollers 52 and the point of contact of sliver 58 with core10, and the-length of individual F1} is rotated at constant peripheralbers in the sliver. On the average, breaks occur somewhere near themidpoint of this distance; but any given break can be widely variantfrom the average. The average spacing of slubs is directly a function ofthe difference in velocities of forwarding of core and sliver 58. Whensliver 58 breaks, a certain amount of time elapses before the free endagain travels to contact core 10. In this time, core 10 has advanced aslub-free distance dependent on its higher velocity. The longer anygiven slub is, the longer is the subsequent section of sliver-free core;and vice versa. Average frequency and length of slubs can be controlledprecisely. The scatter of individual values provides an irregularitywhich is very desirable 'in slub-yarn products.

The above process can be operated so that two or more different slivers58 are separately led to core 10. The feeding rates may differ so thateach sliver produces slubs in the wrapped yarn which differ from theothers in average size and/or frequency. Novel effects also result ifthe slivers differ in color or dyeability. Various other similarlyproduced effects are immediately apparent, such as the use of wrappingyarns 32, 42 differing in color or dyeability.

FIG. 2 very schematically represents a portion 70 of the length of awrapped yarn according to this invention. It is generally round in crosssection, though not necessarily perfectlyround. It has lengths 60 ofenlar'ged cross section, i.e., slubs, between which are nonslubbedportions 62. Slubs 60 are irregular in length and irregularly spacedapart. Examination of cross sections taken through slubs 60 and thosetaken through lengths 62 reveals that slubs contain more fiber ends thando lengths 62. When the slub-forming sliver 58 and the continuous corestrands 16 are composed or recognizably different fibers, it is readilyseen that the slubs 60 are larger solely because they alone containfibers from sliver 58. Wrapping yarns 64 are shown schematically. Theygenerally are helically wrapped around the core, in telescoped forwardand backwound directions. Whether or not they completely hide the corefrom view depends on how many are used. Also, the more wrapping yamsused, the more uniform appears the wrapped layer. Ordinarily, thewrapped slub yarn 50 (FIG. 1) will have numerous small loops of wrappingyarns 32 or 42 extending radially outward to provide a fuzzy appearanceand touch.

FIG. 3 represents a variation of the process of'FIG. l which isparticularly suitable when attachment of the free end of slub-formingsliver 58 to core 10 does not occur sufficiently on bare contact. Thismight be, for instance, when continuous core strands .16 are of straightcontinuous filaments. In this case, core strands 16 are led into thisprocess in at least two separate groups over separate sets of tensionbars 20. They come together at point 66, where first rotatingstanding-wave pattern 22 begins. Nip-rolls 52 and forwarding jet-device54 are set up to deliver sliver 58 point 66 and initiation of twistingtraps the advancing free end of sliver 58 so that a portion is brokenoff to initiate a new slub.

When the core strands 16 are slivers, the slivers for the core andtheslub-forming sliver 58 can be assembled from supplies of stablefibers, using known assembly devices, and fed directly to the wrappingprocess in coupled fashion. Since practically any desirable slubsize orslub-frequency can be obtained in practicing this invention, it is notlimited to any particularones.

The following example illustrates a specific embodiment of the processand product of this invention.

EXAMPLE 1 A process as depicted in FIG. I is used to make a novelwrapped yarn with slubs irregularly distributed along its length. It iscomposed of fibrous polyhexamethylene adipamide. Core 10 is formed byleading together four ends of sliver, each end being about 1,500 denierand composed of staple with a maximum length 5Y2 inches (5.08 cm.).Sliib forrning sliver 5 8 is a single end of the kind of sliver used incore'10. The 40-denier wrapping yarns employed are each composed of 13continuous filaments. Ten wrapping'yarns 32 and ten wrapping yarns 42are employed, each group being fed to a 3- to 4-inch (7.6 to 10.2 cm.)length of core 10 upstream of its respective torque-jet twister.Center-tocenter spacing of the torque-jet twisters is 14.5 inches (36.8cm.). I

Each torque-jet twister has an axial torque chamber (yarn passage) whichis 0.625 inch (1.59 cm.) in diameter and 0.375 inch (0.95 cm.) long.Pressurized air is fed tangentially to the torque chamber at itslengthwise device 54 is simply a tube along which air flows to carrysliver 58 away from'rolls 52 and to direct its free end into contactwith core 10. Air at a pressure of 5 psig. (0.35 kg./cm. gage) isinjected into jet-device 54.

The wrapped yarn so produced is characterized as follows: (1) its denieris approximately 7,000; (2) its slubs have cross-sectional areas about20% greater than the nonslubbed cross-sectional areas; the averagespacing between slubs is about 19 inches (48.3 cm.) with a minimum ofabout 8 inches (20.3 cm.) and a maximum of about 30 inches (76.2 cm.);and the average length of each slub is about 3.5 inches (8.9 cm.) with aminimum of about 2.0 inches (5.1 cm.) and a maximum of about 5.5 inches(14.0 cm.). I

DESCRIPTION OF AN ADDITIONAL EMBODIMENT In the process of FIG. 4, allmovemenet of core 10 through the apparatus is provided by rotation ofroll 51 against its nip-roll 53. As indicated, roll 51 is driven by adevice which may either manually or automatically be turned on and offfor preselected intervals of time, either constant or variable. Numerousmethods may be used for winding the wrapped product 50. One conve nientone, as shown, winds yarn 50 on sleeve 55 rotated by air motor 57. Motor57 can be operated continu ously at such a setting that it rotatessleeve 55 only when roll 51 is rotated, thus always taking up the slack.Preferably yarn 50 goes through fixed guide 59 and then through traverseguide 61, the latter reciprocating laterally during rotation of sleeve55.

Core yarns l6, unwound from supply package 18, are led around tensionbars 20 into the rotating standing wave pattern 22 upstream of firsttorque-jet false twister 24. Partially wrapped yarn 30 passes throughthe longitudinal passage of twister 24 in which it is false-twisted by avortex of air generated by injecting air tangentially into the passagevia pipe 26. A plurality of spaced continuous-filament wrapping yarns 32from creel 34 is led freely to the standing-wave pattern 22. Partiallywrapped yarn 30 continues through the second rotating standing-wavepattern 36 established by torque-jet false twister 38 just as is done bytwister 24 except that air inlet 40 is reversed to produce an oppositelyrotating vortex. A second set of wrapping yarns 42 is freely led tostanding wave pattern 36 from creel 44. A snubbing guide 46 preventstwist of twister 38 from influencing the operation of twister 24.

This process is used to produce slub yarn products of the type indicatedin FIG. 5. Lines 64 represent the reversing helical wrappings of yarns32 and 42 formed as core is moving. If only a few wrapping yarns 3 2, 42are used, core 10 will not appear uniformly wrapped and will be visiblein spots. The more wrapping yarns supplied, the more uniform and opaquebecomes the wrapping. When core 10 stops, however, each wrapping yarn 32or 42 winds about core 10 in a plane substantially perpendicular to theyarn axis, thus forming tight rings 63 around the yarn. It is notnecessary that yarns 32 and 42 be guided from their creels 34 and 44.Usually, however, there will be at least one guide for each not farremoved from the respective standingwave patterns 22 and 36. Thus, yarns32 and 42are reasonably constantly spaced from one another to formfairly uniformly spaced rings 63. Depending on spacing I selected, thelatter may or may not touch or overlap. When wrapping occurs in two (ormore) consecutive standing-wave patterns 22, 36,'it is easy to adjustthe distance between stopping of roll 51 so that the second set of rings63 is superposed on a previously formed EXAMPLE 2 A novel bulky yarn ismade using the process of FIG. 4. It is totally composed of fibrouspolyhexamethylene adipamide. Four ends of sliver, each of which is about1500 denier and consists of staple fibers of up to 2 inches (5.08 cm.)in length, are combined to form the core. Twenty wrapping yarns areused, each of which is a 40-denier yarn of 13 continuous filaments. Tenwrapping yarns 32 are guided to core 10 along a distance of from 3 to 4inches (7.64 to 10.16 cm.) of corelength, and 10 wrapping yarns 42 aresubsequently guided to the core along 3 to 4 inches of core'length asillustrated.

Each of torque jets 24, 38 has a longitudinal torque chamber which is0.625 inch (1.58 cm.) in diameter and 0.375 inch (0.95 cm.) inaxiallength. Feeding tangentially to the torque chamber at itslengthwisemidpoint is an orifice 0.156 inch'(0.397 cm.) indiameter into whichpressurized air is injectedA ir pressure for torque jet 24 is 45 psig.(3.16 kg./cm gage); for torque jet 38 it is 60 psig. (4.22 kg./cm. gage)and is injected to produce counterrotation.

Center-to-center separation of the torque jets is 14.5 I

inches (36.8 cm.), and center-to-center separation of wrapping lengthsupstream of each torque jet is about 13 inches (33.0 cm.). Rate of coreadvancement is about yd./min. (137.2 m./mi-n.); thelength of eachadvancement is 19 to 20 inches (48-51 cm); and the time the core iscompletely stopped between advancements is about 3 seconds. Each slub isfrom 3 to 4 inches (7.62 to 10.16 cm.) long, has a cross-sectional areaabout 30% greater than that of nonslubbed portions, and has numerousfuzzy loops of wrapping yarn extending from its surface. In contrast tothe helicaltype wrappings apparent on the surface between slubs, the layof wrappings in the slubs is essentially perpendicular to the core-axis.

I claim:

1. A slub yarn product comprising a fibrous core and a wrapped layer ofcontinuous yarns which extends completely along the core with wrappingyarns winding about the core alternately in S and Z twist directions andbackwinding about previous windings in tight portions at randomintervals along. the core, the yarn product being characterized by slubswhich have crosssectional areas from 15 percent to 35 percent greaterthan the average cross-sectional area of the nonslubbed portions.

2 A slub yarn product as defined in claim 1 wherein the wrapped layercomprises a plurality of continuousfilament yarns. v

3. A slub yarn product as defined in claim 1 wherein the fibrous corecomprises a. plurality of strands of discontinuous fibers.

4. A slub yarn product as defined in claim 1 wherein the slubs resultfrom a greater number of core fibers in slub portions than in nonslubbedportions of the product.

5. A slub yarn product as defined in claim 1 wherein, the wrapped layerhas a preponderance of wrappings at slub portions of the product.

6. A slub yarn product as defined in claim 1 wherein the slubs haverandom lengths between 2 and 5.5 inches and are randomly spaced atdistances of 8 to 30 inches between slubs.

7. A slub yarn product as defined in claim 6 wherein the fibrous core iscomposed of discontinuous fibers and is between 5,000 and 9,000 denierin size, the wrapped layer is composed of continuousfilament yarns, andthe denier of the yarn product is between 6,000 and 10,000.

8. Ina process for preparing a wrapped yarn product by continuouslyadvancing a core strand through a series of false-twisting devices toform rotating standing waves and simultaneously feeding wrapping yarnsto the rotating standing waves, the improvement whichcomprises feeding asliver of discontinuous fibers at a lower speed than the advancing corestrand so that sliver is intermittently caught in the core, and causedto break into portions spaced along the core, and is then wrapped aspart of the core to form a slub yarn product.

9. A process as defined in claim 8 wherein said sliver is fed to theadvancing core strand in a jet of air.

10. A process as defined in claim 8 wherein a plurality of strands arecontinuously combined to form the advancing core and said sliver is fedto the core between combining strands.

1. A slub yarn product comprising a fibrous core and a wrapped layer ofcontinuous yarns which extends completely along the core with wrappingyarns winding about the core alternately in S and Z twist directions andbackwinding about previous windings in tight portions at randomintervals along the core, the yarn product being characterized by slubswhich have cross-sectional areas from 15 percent to 35 percent greateRthan the average crosssectional area of the nonslubbed portions.
 2. Aslub yarn product as defined in claim 1 wherein the wrapped layercomprises a plurality of continuous-filament yarns.
 3. A slub yarnproduct as defined in claim 1 wherein the fibrous core comprises aplurality of strands of discontinuous fibers.
 4. A slub yarn product asdefined in claim 1 wherein the slubs result from a greater number ofcore fibers in slub portions than in nonslubbed portions of the product.5. A slub yarn product as defined in claim 1 wherein the wrapped layerhas a preponderance of wrappings at slub portions of the product.
 6. Aslub yarn product as defined in claim 1 wherein the slubs have randomlengths between 2 and 5.5 inches and are randomly spaced at distances of8 to 30 inches between slubs.
 7. A slub yarn product as defined in claim6 wherein the fibrous core is composed of discontinuous fibers and isbetween 5,000 and 9,000 denier in size, the wrapped layer is composed ofcontinuous-filament yarns, and the denier of the yarn product is between6,000 and 10,000.
 8. In a process for preparing a wrapped yarn productby continuously advancing a core strand through a series offalse-twisting devices to form rotating standing waves andsimultaneously feeding wrapping yarns to the rotating standing waves,the improvement which comprises feeding a sliver of discontinuous fibersat a lower speed than the advancing core strand so that sliver isintermittently caught in the core, and caused to break into portionsspaced along the core, and is then wrapped as part of the core to form aslub yarn product.
 9. A process as defined in claim 8 wherein saidsliver is fed to the advancing core strand in a jet of air.
 10. Aprocess as defined in claim 8 wherein a plurality of strands arecontinuously combined to form the advancing core and said sliver is fedto the core between combining strands.